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Performance

· 14 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
84
GRADE
B
FIX
0
REVIEW
4
PASS
8
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
88
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
95
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
81
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

954 ms

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

2.02 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

86 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.001

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

1.39 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

2.42 s

Page Load Progression

375 ms
750 ms
1.1 s
1.5 s
1.9 s
2.2 s
2.6 s
3.0 s
Checks
14
8 PASS 4 REVIEW
B
Page Weight Budget
1.5 MB transferred, 62 requests
REVIEW
1.5 MB transferred, 62 requests
Info::
Page weighs 2.8 MB (1.5 MB transferred)
Info::
62 HTTP requests
Info::
Estimated 0.32 g CO2 per page load
1.5 MB / 2.4 MB budget
1.5 MB transferred
62 requests
0.32 g CO2 per page load
Images 923.8 KiB 59%
JavaScript 404.1 KiB 26%
Fonts 141.4 KiB 9%
CSS 63.9 KiB 4%
HTML 19.4 KiB 1%
Other 2.2 KiB 0%
Other 2.2 KiB 0%
0 2.4 MB 4.9 MB
Approaching limit
B
Image Optimization
33 images, 0 KB saveable
REVIEW
33 images, 0 KB saveable
Info::
All images are well-optimized
33 images 924 KB
0 oversized -0 KB
5 legacy format
0 missing dimensions CLS risk
B
JS Execution Cost
919ms total JS execution
REVIEW
919ms total JS execution
Warning::
https://www.ox.ac.uk/sites/files/oxford/advagg_js/...: 271ms CPU time
Info::
https://www.ox.ac.uk/: 232ms CPU time
Info::
Unattributable: 161ms CPU time
Info::
https://www.googletagmanager.com/gtm.js?id=GTM-TDB...: 146ms CPU time
Info::
https://cc.cdn.civiccomputing.com/9/cookieControl-...: 109ms CPU time
Info::
Third-party scripts: 416ms (45% of total)

Main Thread Breakdown

Script Evaluation 39% Style & Layout 27% Other 20% Script Parsing & Compilation 6% Parse HTML & CSS 4%
ScriptTotalScriptingParse/CompileParty
https://www.ox.ac.uk/sites/files/oxford/advagg_js/js__ihdwYz7z62m5viS1EMhNOpB9bfVJ_3N7-eC3gKeS-sI__ATnX8WF8ltra-g2RmFaF163qjG6u_xdvxVSENyHJmQk__h7T-cjtV_dUO9EYp5xzvQZuTpmuCIt2rzPKmYSUARw8.js271ms136ms7ms1st
https://www.ox.ac.uk/232ms4ms2ms1st
Unattributable161ms3ms0ms3rd
https://www.googletagmanager.com/gtm.js?id=GTM-TDB29T146ms114ms22ms3rd
https://cc.cdn.civiccomputing.com/9/cookieControl-9.x.min.js109ms91ms18ms3rd
C
JS Bundles
Action
11 scripts, 149 KB unused
REVIEW
11 scripts, 149 KB unused
Warning::
https://www.googletagmanager.com/gtm.js?id=GTM-TDB...: 66 KB unused (48%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://cc.cdn.civiccomputing.com/9/cookieControl-...: 57 KB unused (46%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.ox.ac.uk/sites/files/oxford/advagg_js/...: 26 KB unused (55%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://www.ox.ac.uk/sites/files/oxford/advagg_js/...: unminified — 13 KB could be saved
Warning::
https://www.ox.ac.uk/sites/files/oxford/advagg_js/...: unminified — 10 KB could be saved
Info::
Total unused JavaScript: 149 KB
149 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtm.js?id=GTM-TDB29T138 KB66 KB (48%)✓3rd
https://cc.cdn.civiccomputing.com/9/cookieControl-9.x.min.js123 KB57 KB (46%)✓3rd
https://www.ox.ac.uk/sites/files/oxford/advagg_js/js__9q_RhUzRB9SYU1-amhF7x_iVsHaJWYLCy9mGerNNw8c__r14_gMXz1ZbCtJf3hugZI-ClIj-6kYYT4Zc-iywNTA4__h7T-cjtV_dUO9EYp5xzvQZuTpmuCIt2rzPKmYSUARw8.js46 KB26 KB (55%)✗1st
https://www.ox.ac.uk/sites/files/oxford/advagg_js/js__SlxZR0T0y0knhPGspoKKlEQqbk_RdNNsHwLrlCQRTSo__jRyIJdNHHPQDI24D74GCcZq-Uqnrf4Vs1Wh5VKn50M0__h7T-cjtV_dUO9EYp5xzvQZuTpmuCIt2rzPKmYSUARw8.js1 KB—✓1st
https://www.ox.ac.uk/sites/files/oxford/advagg_js/js__ihdwYz7z62m5viS1EMhNOpB9bfVJ_3N7-eC3gKeS-sI__ATnX8WF8ltra-g2RmFaF163qjG6u_xdvxVSENyHJmQk__h7T-cjtV_dUO9EYp5xzvQZuTpmuCIt2rzPKmYSUARw8.js45 KB—✗1st
https://www.ox.ac.uk/sites/files/oxford/advagg_js/js__z5ONFBC5kmHZRZuHWswENYjC0rzf40bh_hB_Fs0eyLo__WcT3Q2crdrKi2EHa4S2isbSrXXO5RbKkDpvVkjhTmaY__h7T-cjtV_dUO9EYp5xzvQZuTpmuCIt2rzPKmYSUARw8.js10 KB—✗1st
https://www.ox.ac.uk/sites/files/oxford/advagg_js/js__9o6MTP80DXWHri8ze4nKy9qC5QYGmn5CmTwGsjeqoRs__t7QMh2Q0VAdZOqg2nX8lHHSSz0oEF4l8S4NpWKqSdpE__h7T-cjtV_dUO9EYp5xzvQZuTpmuCIt2rzPKmYSUARw8.js1 KB—✓1st
https://www.ox.ac.uk/sites/files/oxford/advagg_js/js__g6HAL4XtohiHzS9CG4SIugqNOzdAq58xVph4DbYxlNE__o1_7j2Bpaj2feiS_rkUK_CGonKU4T-Mdv49O47LYHOc__h7T-cjtV_dUO9EYp5xzvQZuTpmuCIt2rzPKmYSUARw8.js12 KB—✗1st
https://static.cloudflareinsights.com/beacon.min.js/v8c78df7c7c0f484497ecbca7046644da177152312451611 KB—✓3rd
https://sjs.bizographics.com/insight.min.js17 KB—✓3rd

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

Consider code splitting or tree shaking to reduce unused code.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

A+
Third-Party Impact
19% third-party, 0 ms blocking
PASS
19% third-party, 0 ms blocking
Info::
Third-party code accounts for 19% of page weight (292.3 KiB of 1.5 MiB)
Info::
Third-party blocking time is low (0 ms)
81%
19%
First-party Third-party
A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Font Loading
3 fonts (141 KB)
PASS
3 fonts (141 KB)
Info::
3 font(s) use font-display: swap (FOUT risk but functional)

Web fonts

3

141 KB total

Render-blocking

0

of 3

Dominant font-display

swap

Most common across fonts

Font loading timeline
Transfer FOIT (block) FOUT (swap)
0 ms 500 ms 1.0 s 1.5 s 2.0 s FCP 954 ms LCP 2.0 shttps://www.ox.ac.uk/cf-fonts/s/pt-sans/5.0.11/latin/400/normal.woff2normal.woff2 https://www.ox.ac.uk/cf-fonts/s/pt-sans/5.0.11/latin/400/normal.woff2 — 44.7 KiB — 0 ms — font-display: swaphttps://www.ox.ac.uk/cf-fonts/s/pt-sans/5.0.11/latin/700/normal.woff2normal.woff2 https://www.ox.ac.uk/cf-fonts/s/pt-sans/5.0.11/latin/700/normal.woff2 — 46.3 KiB — 0 ms — font-display: swaphttps://www.ox.ac.uk/cf-fonts/s/pt-sans-narrow/5.0.19/latin/700/normal.woff2normal.woff2 https://www.ox.ac.uk/cf-fonts/s/pt-sans-narrow/5.0.19/latin/700/normal.woff2 — 50.4 KiB — 0 ms — font-display: swap
normal.woff2 woff2 swap
Size 45 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
normal.woff2 woff2 swap
Size 46 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
normal.woff2 woff2 swap
Size 50 KB
Load time 0 ms
Start 0 ms
Risk FOUT — text flashes from fallback to web font
Optimization checklist
  • Preload critical fonts (priority=high)
  • Use woff2 format for all fonts
  • Set font-display to swap, optional, or fallback
  • Subset large fonts (≤100 KB each)
A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
No optimization needed
PASS
No optimization needed
Info::
No resource hint issues
A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

A+
HTTP Caching
max-age=1800 (30 minutes)
PASS
max-age=1800 (30 minutes)
Info::
Cache-Control header is set
Got: public, max-age=1800
Info::
Effective TTL: 30 minutes (max-age=1800)
Info::
Last-Modified header present
Cache-Control

public, max-age=1800

DirectiveValueMeaning
public—Any cache may store this response
max-age1800Cache for 30 minutes
Effective TTL: 1800 seconds
Network Waterfall
62 requests over 0ms
INFO

Performance analysis not available for this result.

Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
45% of JavaScript execution is third-party
First-party Third-party 416ms · 261KB · £4/mo
Unattributable
Other
Optional
Execution 161ms
Transfer 0 KB
Monthly Cost £2/mo
Google Tag Manager
Tag Manager
Optional
Execution 146ms
Transfer 138 KB
Unused 48%
Monthly Cost £2/mo
cc.cdn.civiccomputing.com
Other
Optional
Execution 109ms
Transfer 123 KB
Unused 46%
Monthly Cost £1/mo

45% of JavaScript execution time comes from third-party scripts.

Why this matters

Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.

Learn more ▾

Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.

Source: web.dev / HTTP Archive Web Almanac

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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